Carbonated beverage dispensing machines normally include a carbonated water supply in the form of a water reservoir to which CO.sub.2 under pressure is supplied and the gaseous head of CO.sub.2 in this reservoir is used to expel the carbonated water when a dispensing nozzle is opened. Consequently, the carbonated water supply in the reservoir is gradually depleted and must be replenished periodically by a pump having its inlet connected to fresh water source. Various means have been used to assure an adequate supply of carbonated water.
Also, such machines pass the carbonated water through a coil located in a coolant water reservoir, which reservoir also contains a refrigerant evaporator coil which is used to build up an ice mass or "bank" thereon to assure the proper temperature of coolant water. Various means, usually in the form of timing devices, have been used to control the size of the ice mass or bank.